The overall goal of the Special Center of Research on the Genetics of Conotruncal Cardiac Defects (SCOR) is to investigate the molecular genetic basis of conotruncal cardiac development and disease. The role of the Clinical Core has been to recruit patients with conotruncal cardiac defects for chromosome 22q11 deletion screening and to gather pertinent medical/family information for phenotype/genotype analyses performed by the scientific projects. Although this work continues, efforts to identify genetic etiologies of conotruncal malformations other than the 22q11 deletion have been proposed and initiated in the renewed SCOR (commencing 1/99). In particular, candidate genes for these disorders will be evaluated either by direct mutation analysis or non-parametric linkage analyses. To perform such investigations, parental, sibling as well as proband DNA must be available for analysis. To this end, blood or buccal swab samples from parents and siblings are now requested as well as that of the proband. The GCRC nurses have drawn these additional samples on consenting adults and children. The GCRC nurses have greatly facilitated the Core's ability to obtain the additional samples from family members without which the investigations could not be performed. The SCOR clinical core has been recruiting probands with conotruncal cardiac defects since 1/94 and has recruited a total of 559 patients to date. Parental and sibling samples have only been routinely requested since the initiation of the GCRC protocol (#1642). Thus, only 23 parents or siblings have had venipuncture performed by the GCRC nurses. Buccal swabs for DNA extraction have been obtained by the Core from other parents unwilling to undergo venipuncture or from families who have already left the hospital before we could coordinate venipuncture. Although laboratory and epidemiologic investigations are ongoing, analysis using parental samples will not be completed until a significantly increased number are obtained.